Drill bit



- member shown in Patented Jan. 6, 1942 mum. arr

Medord Joseph Potvin, Siscoe, Quebec, Canada.

Application May 29, 1940, Serial No. 331,149

6 Claims. (Cl. 25%") This invention relates to drill bits of the type employed in the drilling of rock and overburden such as packed sand and boulders.

An object of the invention is to provide a bit that is efficient in use and economical in operation in that diamond wear is reduced to a minimum. A further object is to provide a bit that is particularly well adapted for drilling overburden and that will readily overcome various overburden drilling diificulties attendant on the use of ordinary bits. A further object is to provide a rock coring or reaming bit the use of which is free from many usual operating dimculties.

The invention resides broadly in the provision of a unitary bit member having the lower portion of its outer side wall provided with a downwardly converging gently stepped taper, the lower faces or shoulders of the steps being set with diamonds for drilling purposes.-

The invention will be described with reference to the accompanying drawing, in which Figure 1 is a longitudinal section of one form of drill assembly in accordance with the invention,

Figure 2 is an end view of the assembly shown in Figure l,

Figure 3 is a side elevation of the drill bit Figure l, V

Figure 4 is a side elevation of another form of drill bit member,

Figure 5 is a longitudinal section view of the member shown in Figure 4, and

Figure 6 is an end view of the member shown in Fi ure 4.

Referring to Figures 1, 2 and 3 of the drawing, l is a one-piece-drill bit member in accordance with the invention comprising a substantially cylindrical body havingan enlarged upper portion 2 and a lower portion the outer surface-of which is provided with shallow steps 3 forming a gentle downwardly converging stepped taper on such outer surface. On the lower face or shoulders of such steps are set diamonds l to constitute a series of spaced concentric annular cutting surfaces. The member may be provided at opposite sides with water grooves 5 and may be cored as indicated at 8.

For association in a drilling assembly, the bit member is internally threaded at either end. An ordinary diamond drill bit 1 may be screwed into the lower end of the member. end of-the member is connected to a standard drill rod 8 by means of a core barrel 9, the outer side surface of which is tapered to provide a member.

and water passage 9.

substantially uninterrupted connecting surface between the enlarged portion 2 of the bit member and the drill rod which is somewhat smaller in diameter than the enlarged portion of the bit The core barrel is of a length to best meet operating conditions and to ensure a taper of rather gentle inclination.

The drill rod has a central water passage l and the core barrel has a single central core The contacting faces of the bit member I with bit I and core barrel 8 are slightly tapered as shown at It and II.

Referring to Figures 4, 5 and 6, a bit member If, constituting the bit, is shown having an enlarged upper portion l3 and a lower portion the outer surfaceof which is stepped as indicated at ll to provide a gentle downwardly converging stepped taper similar to that provided on the bit member disclosed in Figures 1, 2 and 3. The shoulders of the steps H are set with diamonds I! bit, which is adapted to constitute a drilling face isalso-set with diamonds IS. The bit is cored at H and provided with a threaded extension I! for incorporation in a \drill rod assembly.

It will be understood that, for certain types of drilling, the core passages shown in the bits described may be omitted.

The distribution of the diamond drilling surfaces of the bit over the plurality of stepped shoulders, results in a marked decrease in diamond wear during operation since each step is it is usual to provide but a single flat adapted to take but a very small bite out of the rock or other material being drilled. At present, diamond drilling surface on bits with resultant heavy wear on such surface. It has been proposed to provide a smooth. tapered surface on bits with diamonds set in such smooth surface. However, to be effective, this arrangement requires a large number of diamonds to substantially cover the surface. I Otherwise portions of the bit, exposed on the tapered surface between successive diamonds, wear away themselves weakening caulking of the diamonds in the bit. It will be observed that the drill bit of the present invention provides diamond drilling surfaces all of which are in transverse flat planes parallel to the primary drilling face of the bit.

The drill bit assembly described is also useful in avoiding the caving in or sloughing of'the holes being drilled. Due to the very small bite taken out of the sides of a hole by each step,

unitary drill and the lower endface of the the material on such sides is subjected to minimum disturbance.

The drill bit assembly shown in Figure l is particularly emcacious'in the placing or driving of use of pipe of sufficiently heavy guage to permitdriving may be avoided and a light casing pipe employed instead, when a hole is prepared therefor with the. drilling assembly described. The cost of piping is thereby much reduced.

The backwardly converging taper on the core barrel permits the ready withdrawal of the drill assembly from the hole with no disturbance to the material on the sides thereof.

It will be apparent thatmany changes may be made in the drill bit members and drill bit assembly described without departing from the essential features of the invention as defined in the appended claims.

I claim:

1. In a drill, a generally cylindrical bit having a single plane cutting face on its lower end and a plurality of inwardly directed and downwardly ,converging steps on its outer side surface adjacent said lower end, the lower-faces of said steps being disposed at right angles to the longitudinal axis of the bit and being relatively narrow, the side faces of said steps being relatively wide, said lower faces constituting axially spaced annular cutting faces, and diamonds set in said cutting faces.

2. In a drill, a generally cylindrical bit having a single plane cutting face on its lower end and a plurality of inwardly directed and downwardly converging steps on its outer side surface adjacent said lower end, the lower faces of said steps being disposed at right angles to the longitudinal axis of the bit and being relatively narrow, the side faces of said steps being parallel to the longitudinal axis of the bit and being at least several times wider than said lower faces, said lower faces constituting axially spaced annular cutting faces, and diamonds set only in said cutting faces.

3. In a drill, a generally cylindrical bit having a single plane cutting face .on one end thereof, the diameter of said cutting face constituting the major portion of theoverall diameter of the bit, said bit also having on its outer side surface adiacent said end a plurality of inwardly directed and downwardly converging shallow steps, the lower faces of said steps constituting narrow annular and concentric cutting faces, said faces being disposed at right angles to the axis of said bit, and diamonds set in said faces.

4. Ina drill, a generally cylindrical unitary cored bit member,'a coring bit detachably se-.

cured to the lower end of said member, the diameter of said bit approximating at least the major portion ,of the overall diameter of said member, said member having on its outer side surface adjacent said lower end a plurality of inwardly directed and downwardly converging shallow steps, the lower faces of said steps constituting narrow annular and concentric cutting faces, said faces being disposed at right angles to the axis of said bit, and diamonds set in said faces.

5. In a drill, a generally cylindrical unitary cored bit, the diameter of the lowerend of said bit being less than but approximating at least the major portion of the diameter of the upper end portion of said bit, the outer side surface of said bit having a plurality of inwardly directed and downwardly converging shallow steps leading from said upper portion to said lower end, the lower faces of said steps being disposed at right angles to the axis of said bit and being set with diamonds, a drill rod of smaller diameter than said upper end portion of the bit, and a cored barrel member connecting said rod with said upper end portion, the outer side surface of said barrel member having an upwardly converging taper to provide an uninterrupted connecting surface between that of the upper end portion and that of the rod.

6. In a rock drill, a generally cylindrical'unit- MEDORD JOSEPH Po'rvm. 

